As is known in the art, microvias are minute holes drilled by a laser to generate the electrical connection between the layers in a multilayer circuit board. The microvia is typically a solid copper filled via with an aspect ratio ≤1:1 where the aspect ratio=microvia height divided by microvia diameter (taken at the top of the microvia hole). A microvia is used to connect RF, power and logic signal transmission lines to fine-pitch, high pin count active MMICs (monolithic microwave integrated circuit), ASICs and plastic quad flat packages. Microvia interconnect technology enables: High density component layout on Printed Wiring Boards (PWBs). Microvias may use a direct solder reflow interconnect to component signal pad (e.g., MMIC and/or passive component); eliminate a “fan-out” pad from a plated through hole (PTH); and reduces parasitic inductance: critical for RF and high speed digital signals.
In many applications it is required to connect electrical outputs of a Microwave Monolithic Integrated Circuit (MMIC) to a larger microwave component. It also sometimes required to supply power and logic signals to such component. A multi-level printed circuit board (PCB) may be required to make these connections between the MMIC and the microwave component using coaxial connectors. The center coaxial connector would have one end connected to the solder ball and the other end connected to a much larger contact pad. For example, the solder ball of the MMIC may have a diameter of 0.006 inches and the contact pad to connect to the microwave component may have a have a diameter of 0.066 inches.